1. Field of the Invention
The invention relates to a car glazing, particularly a vertically adjustable side glazing, formed from composite glass comprising two thermally tempered individual glazings interconnected by a thermoplastic intermediate layer.
2. Discussion of the Background
A lowerable car glazing of composite type is known from German Utility Model 89 10 916. In this type of side glazing the outer individual glazing of the composite has a thickness of 3 to 4 mm and has the standard tempering typical of a safety glazing which is formed from a single glazing. The inner individual glazing of the composite has a thickness of 1.5 to 2.5 mm and has no tempering or only a very slight tempering. The inner individual glazing also has smaller dimensions than the outer, tempered glazing and the projecting marginal area of the tampered, outer glazing is used for guiding the composite glazing in the guide rails of the window frame. The two individual glazings are interconnected with the aid of a 0.38 to 2.0 mm thick thermoplastic film.
This known glazing must, as a result of its construction, greatly inhibit break-in and penetration through the structure, whilst also having a high sound insulation property. The break-in and penetration-inhibiting action is based on the relatively thick thermoplastic intermediate layer and the fact that the non-tempered or only slightly tempered inner individual glazing is not destroyed even when the outer, tempered glazing is destroyed because the thick intermediate layer protects it. In the case where both glazings are destroyed the composite breaks into very large fragments, so that the window opening remains closed. Therefore when breaking through the side glazing is desired, namely in the case of an accident, the high strength of prior art side glazings prevent rapid break-through and rapid access to the vehicle occupants.
The present invention provides a side glazing made from composite glass which, unlike the aforementioned car side glazing, offers superior safety in case of an accident, has a simple construction and can be manufactured with known production equipment.